Cutting burr shank configuration

ABSTRACT

A cutting burr that includes a pair of axially spaced diamond-shaped portions designed to be keyed into a spindle of a locking mechanism of a high speed surgical drilling instrument and adapted to fit into a single pawl thereof to lock said cutting burr in place so as to prevent axial movement thereof and provide concentric rotation of said cutting burr without any wobbling. The orientation of both portions may be identical with respect to a center plan and diamond shape in the portion at the proximal end of the shank of the cutting tool may be larger than the intermediately located diamond shape of the other portion. The apexes of the facets of the six-sided diamond shape may be disposed below the surface of the shank of the cutting burr.

CROSS-REFERENCE TO RELATED APPLICATIONS

The subject matter described in this application is related to subjectmatter disclosed in the following commonly assigned applications: U.S.patent application Ser. No. 15/818,314 filed Nov. 20, 2017, which is acontinuation of U.S. patent application Ser. No. 15/225,043 (now U.S.Pat. No. 9,820,756) filed Aug. 1, 2016, which is a continuation of U.S.patent application Ser. No. 14/223,011 (now U.S. Pat. No. 9,402,638)filed Mar. 24, 2014, which is a continuation of U.S. patent applicationSer. No. 13/082,016 (now U.S. Pat. No. 8,690,876), filed on Apr. 7,2011, entitled “CUTTING BURR SHANK CONFIGURATION,” which areincorporated herein by reference in their entirety.

BACKGROUND

When performing surgery, surgeons may utilize a surgical drillinginstrument for drilling, cutting or shaping bones that utilize anumerous different kinds and sizes of cutting burrs and attachments.During certain medical operations, the cutting burr needs to be changed.The change must be done timely and efficiently in view of the surgicaldemands. To this end, the portion of the cutting burr, namely, theproximate end of the shank typically lacks a configuration toaccommodate this change of the cutting burr.

SUMMARY

Disclosed herein is a cutting burr that provides for a quick releasethat is fast and simple, and which facilitates the insertion of thecutting burr into a surgical drilling instrument. The cutting burr mayhave a pair of axially spaced six sided diamond-shaped portions, whereone diamond-shaped portion may be formed at an edge of the proximal endof the cutting burr and provides a positive connection with a drivespindle that is connected to a drive motor of the surgical drillinginstrument. A second, axially disposed diamond-shaped portion is adaptedto mate with a locking pawl of the surgical drilling instrument. Thelocking pawl engages the axially disposed diamond-shaped portion to lockthe cutting burr into the surgical drilling instrument withsubstantially no axial movement.

In some implementations, a detent pawl is provided to hold the cuttingburr within the surgical instrument when it is in a loading position.The detent pawl may engage the axially disposed diamond-shaped portionat a side opposite the locking pawl.

In some implementations, the diamond-shaped portion at the proximal endis sized such that it can be used with older surgical drillinginstruments that may not be provided with a complementary receivingrecess for the diamond-shaped portion.

This summary is provided to introduce a selection of concepts in asimplified form that are further described below in the detaileddescription. This summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used to limit the scope of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing summary is better understood when read in conjunction withthe appended drawings. For the purposes of illustration, there is shownin the drawings exemplary implementations; however, theseimplementations are not limited to the specific methods andinstrumentalities disclosed. In the drawings:

FIG. 1 a fragmentary top plan view illustrating the axially spacedsix-sided diamond-shaped cut out portion or portions formed on theproximate end of the shank of the cutting burr;

FIG. 2 is a perspective view of FIG. 1;

FIG. 3 is another prospective view of FIG. 1 slightly turnedillustrating one of the facets in each of the six-sided diamond-shapedportions;

FIG. 4 is another perspective view of FIG. 2 slightly turnedillustrating the top facets of the six-sided diamond-shaped portions;

FIG. 5 is an end view taken along lines 5-5 of FIG. 3 illustrating theshape of the six-sided diamond-shaped portion formed in the cutting burrshank;

FIG. 6 is a sectional view taken along lines 6-6 of FIG. 4 illustratingthe shape of the six-sided diamond-shaped portion and illustrating thedifferent sizes and the orientation of the six-sided diamond portionformed in the cutting burr shank;

FIGS. 7A and 7B illustrate a backwards compatibility of the cutting burrof FIGS. 1-6 within a receiving portion of conventional surgical drill;

FIGS. 8A and 8B illustrate a self-alignment aspect of the diamond-shapedportion at a proximal end of the cutting burr in relation to a keyedslot of a surgical drill;

FIG. 9 is an elevated view of the cutting burr with a spherical shapedcutting bit illustrating the diamond-shaped portions formed in the shankthereof;

FIG. 10 is another elevated view of an example cutting burr; and

FIG. 11 is another elevated view of an example cutting burr.

DETAILED DESCRIPTION

As used herein, the term “cutting burr” may be analogous with terms suchas bit, drill bit, surgical drill bit and the like. The term“attachment” may have several meanings within the text of thisapplication, but when generalized as a component of a surgical drillinginstrument it refers to a portion of the instrument that attaches to theend of the motor/locking mechanism and receives the cutting burr. An“attachment” may be a controlled depth attachment, a minimally invasiveattachment and the like. The surgical drilling instrument may include anintegral motor (electric or pneumatic) and a locking mechanism and anattachment releasably connected to the locking mechanism.

High speed surgical drills are increasingly being used by surgeons whenperforming delicate bone dissection in areas such as the cervical andlumbar spine. Such surgical drills operate at very high R.P.M., and areable to rotationally drive multiple types of attachments and cuttingburrs. As will be described below, a cutting burr of the presentdisclosure includes a shank that defines two substantiallydiamond-shaped portions. The substantially diamond-shaped portionsprovide for ease of insertion and removal of the cutting burr to andfrom a compatible surgical drill. The substantially diamond-shapedportions also enable the surgical drill to direct higher levels oftorque to the cutting burr during surgical procedures.

Referring to FIGS. 1-6, the cutting burr is generally illustrated byreference numeral 10. The attachment portion 12 of the shank 16 of thecutting burr 10 is generally shown as reference numeral 12. A proximalend 14 of the shank 16 is formed with a pair of axially spaced six-sideddiamond-shaped portions 18 and 20. As shown in FIGS. 4 and 5, an uppersurface of portion 18 includes an apex 32 and a pair of facets 34 and 34a also fairing to side edges 34 b and 34 c. The side edges 34 b and 34 cmay be curved to match the radius of curvature of an outer surface ofthe shank 16. As shown in FIGS. 4 and 6, an upper surface 24 of theportion 20 includes apex 26 and a pair of facets 30 and 30 a fairingfrom the apex 26 to the side edges 30 b and 30 c. The side edges 30 band 30 c may be curved to match the radius of curvature of an outersurface of the shank 16.

As shown in the Figs. the diametrical dimensions of the vertices in bothportions is less than the diameter of the main body of the shank. Theshank 16 may include an annular groove 29. The lower surfaces of thepair of six-sided diamond portions 18 and 20 are a mirror image of theupper surface. While the diamond-shaped portions 18 and 20 are describedas being “diamond-shaped,” it is noted that such terminology is intendedto encompass any six-sided (hexagon) shape having a cross-section withflat edges that meet at a six vertices, curved edges that meet at sixpoints, or some combination of both to form the six sides. The flat andcurved edges, and combinations thereof, may be applied to other polygonshapes having different numbers of sides.

The diamond-shaped portion 18 at the outermost proximal end is designedto be inserted into a mating drive portion of a surgical drill, as willbe described with reference to FIGS. 8A and 8B. The diamond-shapedportion 20 is provided as an abutment surface of a retractable lockingpawl of the surgical drill to provide axial locking of the shank 16within the surgical drill. The locking pawl may axially abut theadjacent abutment surface of the diamond-shaped portion 20 to axiallylock the cutting burr 10 in place, thus providing substantially zeroaxial movement. For example, an engagement portion of locking pawl maybe contoured having a generally V-shape with inner surfaces that fitagainst the facets 30 and 30 a of the diamond-shaped portion 20.

As shown in FIG. 3, a back wall 42 may be formed perpendicular withrelation to the central line A and faces a front wall 40 that is taperedfrom the facet (e.g., 30 a) to the outside diameter of the shank 16. Inaccordance with some aspects, an engagement face of the locking pawl mayabut against the back wall 42 to provide axial locking of the cuttingburr 10 within the surgical drill. A tapered front wall 40 mayfacilitate the engagement of the locking pawl into the diamond-shapedportion 20.

The diamond-shaped portion 20 may also be engaged by a detent pawl ofthe surgical drill. For example, an engagement end of detent pawl may becontoured, e.g., having a generally hill shape to partially fit into thediamond-shaped portion 20 on an opposite side of the engagement end ofthe locking pawl. The detent pawl may be provided to apply a sufficientforce on the diamond-shaped portion 20 to allow the cutting burr 10 tobe moved in and out of the surgical drill, while reducing the likelihoodthat the cutting burr will inadvertently fall out of the surgical drillwhen in a loading position.

As shown by the a comparison of the sectional views of thediamond-shaped portions 18 and 20 (FIGS. 5 and 6), the two diamondshapes may be different in size, where the diamond shape indiamond-shaped portion 18 is larger than the diamond shape of thediamond-shaped portion 20. As illustrated, the vertices 32 and 36 fallbelow the outer diameter of the shank 16 and both diamond shapes are inaxial alignment with each other and may be oriented in parallelrelationship. In some implementations, the diamond-shaped portion 20 andthe diamond-shaped portion 18 may be the same size, or thediamond-shaped portion 18 may be larger than the diamond-shaped portion20. In the various configurations, the vertices 26 and 32 ofdiamond-shaped portions 20 and 18, respectively, are along a same lineand in a same plane as the center line A. Exemplary dimensions of thesix-sided diamond diamond-shaped portions 18 and 20 are listed indegrees (°) and inches (″) and may be substantially as follows:

The angle of the facets of the six-sided diamond in the diamond-shapedportion 20−a=47°;

The width of the facets of the six-sided diamond in the diamond-shapedportion 20−b=0.046″;

The width of the facets of the six-sided diamond in the diamond-shapedportion 18−c=0.065″;

The width of the shank 16 at the space between diamond-shaped portions18 and 20−d=0.029″;

The length of the diamond-shaped portion 20−e=0.068″; and

The length between the proximal end and the back wall of diamond-shapedportion 18 f=0.149″. This dimension may contribute to the feature ofsubstantially reducing the axial play of the cutting burr.

Thus, in accordance with the above, the diamond-shaped portions 18 and20 provide sufficient cross-sectional dimensions to meet strength andreliability requirements needed for high-speed, large force surgicalapplications. Facets 34 and 34 a of the diamond shape 18 providepositive engagement surfaces in both clockwise and counter-clockwiserotational directions and are sufficiently sized to withstand rotationsforces in either direction without wobbling within the surgical drill.For example, some surgical drills provide bi-directional rotation,allowing the surgeon to selectively reverse rotation for varioussurgical techniques. In conventional designs, there may be rotationalplay between a bit end and a drive portion. However, the symmetricaldiamond facets 34 and 34 a of the diamond-shaped portion 18 providesubstantial drive surfaces in either direction.

With reference to FIGS. 7A and 7B, the diamond-shaped portion 18 at theoutermost proximal end of the cutting burr 10 is designed to haveunidirectional backward compatibility with older drill instruments inaccordance with aspects of the disclosure. For example, a conventionaldrill instrument may include an insert 106 that defines a generallyrectangular slot 105 having rounded side walls. The rounded side wallsmay be shaped with a radius of curvature that parallels the outer wallof the insert 106. Conventional cutting burrs may include acomplementary generally rectangular portion having rounded side wallsthat is received by the slot 105. The insert 106 may be driven by amotor, thus providing rotational force on the cutting burr.

As shown in FIG. 7A, in accordance with some implementations, facets 34a and 34 d of the diamond-shaped portion 18 engage the inner walls ofthe slot 105. The dimension c of the diamond-shaped portion 18, notedabove, may be sized such that the surface area of the facets 34 a and 34d is substantial enough to withstand the torque provided by the motor ofthe conventional drill instrument. Thus, the cutting burr 10 of thepresent disclosure may be utilized by conventional drill instruments.

Referring now to FIGS. 8A and 8B, in some implementations, the cuttingburr 10 of the present disclosure provides for a level of self-alignmentwithin the insert 106. The insert 106 may be provided in a compatiblesurgical drill and define a diamond-shaped key slot 107, a pointedshaped inlet end 109, and opposing holes 110 that formed in the insert106 for receiving dowel pin which may serve to locate the cutting burr10 when inserted into the key slot 107. The inlet end 109 serves tofacilitate the alignment and insertion of the cutting burr 10 as it isadvanced toward and into the key slot 107 of the insert 106. Forexample, if the diamond-shaped portion 18 is not in alignment with thekey slot 107 (FIG. 8A), a bottom surface of the diamond-shaped portion18 will contact an apex 111 of the inlet end 109 causing the cuttingburr 10 to rotate into alignment with the key slot 107. As such, thecooperative engagement of the diamond-shaped portion 18 and inlet end109 facilitates the easy insertion of the cutting burr 10 into thecompatible surgical drill. As such, the diamond portion 18 serves toprovide a secure connection in the key slot 107.

FIGS. 9, 10, and 11 illustrate different example cutting bits 22provided at a distal end on the shank 16. As described above, the shank16 may include the attachment portion 12. The cutting bits 22 may bemilled or cut-out portions. The cutting burr 10 in FIG. 9 exemplifies afluted ball or drill bit; the cutting burr 10 in FIG. 10 exemplifies adiamond ball; and the cutting burr 10 in FIG. 11 exemplifies a twistdrill. The cutting bits 22 are presented only as examples and are notintended to limit the scope of the present disclosure as numerousvariations are possible.

Thus, as described above, a cutting burr is provided with an attachmentend that has a configuration and dimensions that serve to facilitate theinsertion of the cutting burr into the surgical cutting instrument. Whenlocked in the running position there is a structure that prevents thecutting burr from having any axial movement. Also, there is a positiveconnection such that the cutting burr rotates concentrically without anywobbling motion.

While particular aspects of the present subject matter described hereinhave been shown and described, it will be apparent to those skilled inthe art that, based on the teachings herein, changes and modificationsmay be made without departing from the subject matter described hereinand its broader aspects and, therefore, the appended claims are toencompass within their scope all such changes and modifications as arewithin the true spirit and scope of the subject matter described herein.

1-36. (canceled)
 37. A cutting burr comprising: a shank with anengagement feature at a proximal end of the shank sized and configuredto receive rotational forces from a surgical drilling instrument and acutting bit formed on a distal end of the shank, the engagement featureincluding four planar surfaces, where a first pair of the planarsurfaces includes a first surface and a second surface that meet at afirst apex, where a second pair of the planar surfaces includes a thirdsurface and a fourth surface that meet at a second apex, where the firstand the third surfaces are opposite and parallel each other and thesecond and the fourth surfaces are opposite and parallel each other, aninsert including a slot defined by substantially parallel opposing sidewalls, where the engagement feature is received within the slot and thewidth of the slot measured between the opposing side walls correspondsto a width between the first surface and the third surface of theengagement feature such that shank cannot rotate within the slot whenthe shank is coupled to the insert.
 38. The cutting burr of claim 37,wherein the insert is adapted to be inserted into a complementary shapedmating recess of a surgical drilling instrument, wherein engagementbetween the opposing side walls of the insert and the correspondingfirst or second pair of planar sides of the engagement feature providesrotational forces to the shank.
 39. The cutting burr of claim 37,wherein the slot further includes curved side walls extending betweenthe parallel opposing side walls formed in the slot in the insert. 40.The cutting burr of claim 39, wherein the radius of curvature of thecurved side walls corresponds to a radius of curvature of an outer wallof the insert.
 41. The cutting burr of claim 39, wherein the first pairof the planar surfaces of the engagement feature is joined to the secondpair of the planar surfaces by curved side edges, the first and fourthsurfaces being joined by a first curved side edge and the second andthird surfaces being joined by a second curved side edge, wherein theradius of curvature of the curved side walls of the slot corresponds toa radius of curvature of the first and second curved side edges of theengagement feature.
 42. The cutting burr of claim 41, wherein a diameterof the slot defined at the curved side walls corresponds to a diameterdefined between the first and second curved side edges of the engagementfeature.
 43. The cutting burr of claim 37, wherein the slot defines adiamond-shape in cross-section and is sized and configured to engage thefirst and second pairs of planar surfaces of the engagement feature. 44.The cutting burr of claim 37, wherein the insert further defines apointed-shaped inlet end, where the inlet end facilitates an alignmentand insertion of the cutting burr as it is advanced toward and into theslot, wherein, during coupling, contact between the proximal end of theshank and the pointed-shaped inlet end of the insert causes the shank torotate thereby bringing the engagement feature into alignment with theslot.
 45. The cutting burr of claim 44, wherein the pointed-shaped inletend includes a first tapered surface extending from an outer surface ofthe insert towards a centerline of the insert and a second taperedsurface extending from the outer surface of the insert towards thecenterline of the insert opposite the first tapered surface.
 46. Thecutting burr of claim 37, wherein the insert includes a hole extendingthrough a sidewall of the insert, where a dowel pin received within thehole locates the cutting burr and the engagement feature with in theslot.
 47. The cutting burr of claim 37, wherein the first and the thirdsurfaces of the engagement feature have equal length measured around thecircumference of the shank, wherein the second and fourth surfaces ofthe engagement feature have an equal length from the second lengthmeasured around the circumference of the shank.
 48. The cutting burr ofclaim 37, wherein the width of the engagement feature measured betweenthe first apex and the second apex is less than a diameter of the shank.49. The cutting burr of claim 37, wherein the first apex and the secondapex are in axial alignment.
 50. The cutting burr of claim 37, whereinthe engagement feature extends from the proximal end of the shank to atapered surface extending from each of the four planar surfaces to anouter surface of the shank.
 51. The cutting burr of claim 37, whereinthe first pair of the planar surfaces and is joined to the second pairof the planar surfaces around the circumference of the shank by curvedside edges, the first and fourth surfaces being joined by a first curvedside edge and the second and third surfaces being joined by a secondcurved side edge, wherein the curved side edges have a radius ofcurvature corresponding to an outermost radius of curvature of theshank.
 52. A surgical instrument including: a surgical drillinginstrument including a motor and a locking mechanism; a cutting burrreleasably connected to the locking mechanism and receiving rotationalforces output from the motor, the cutting burr comprising: a shank withan engagement feature at a proximal end of the shank sized andconfigured to receive rotational forces from a surgical instrument and acutting bit formed on a distal end of the shank, the engagement featureincluding four planar surfaces, where a first pair of the planarsurfaces includes a first surface and a second surface that meet at afirst apex, where a second pair of the planar surfaces includes a thirdsurface and a fourth surface that meet at a second apex, where the firstand the third surfaces are opposite and parallel each other and thesecond and the fourth surfaces are opposite and parallel each other, aninsert including a slot defined by substantially parallel opposing sidewalls, where the engagement feature is received within the slot and thewidth of the slot measured between the opposing side walls correspondsto a width between the first surface and the third surface of theengagement feature such that shank cannot rotate within the slot whenthe shank is coupled to the insert.
 53. The surgical instrument of claim52, wherein the four planar surfaces of the engagement feature areadapted to accept rotational engagement forces of the motor, wherein thelocking mechanism engages the cutting burr to fix the axial position ofthe cutting burr with respect to the surgical drilling instrument. 54.The surgical instrument of claim 52, wherein the first pair of theplanar surfaces of the engagement feature is joined to the second pairof the planar surfaces by curved side edges, the first and fourthsurfaces being joined by a first curved side edge and the second andthird surfaces being joined by a second curved side edge, wherein theslot in the insert includes curved side walls extending between theparallel opposing side walls formed in the slot in the insert, theradius of curvature of the curved side walls of the slot correspondingto a radius of curvature of the first and second curved side edges ofthe engagement feature.
 55. The surgical instrument of claim 52, whereinthe slot defines a diamond-shaped slot sized and configured to engagethe first and second pairs of planar surfaces of the engagement feature.56. The surgical instrument of claim 52, wherein the insert furtherdefining a pointed-shaped inlet end, and wherein the inlet endfacilitates an alignment and insertion of the cutting burr as it isadvanced toward and into the slot, wherein, during coupling, contactbetween the proximal end of the shank and the pointed-shaped inlet endof the insert causes the shank to rotate thereby bringing the engagementfeature into alignment with the keyed slot, wherein the pointed-shapedinlet end includes a first tapered surface extending from an outersurface of the insert towards a centerline of the insert and a secondtapered surface extending from the outer surface of the insert towardsthe centerline of the insert opposite the first tapered surface.